Abu Dawud said: I asked Ahmad (b. Hanbal): What is hoarding (hukrah) ? He replied: That on which people live.
Abu Dawud said: Al-Auza'i said: A muhtakir (one who hoards) is one who withholds supply of goods in the market.
In-book : Book 24, Hadith 32
English translation : Book 23, Hadith 3440